In the recent debate in the sociology of the sciences about transdisciplinarity, Mode-2 science is heralded as inducing a new disciplinary structure of science and scientific research. We argue that this debate can be interpreted as a continuation of an older discussion about two conflicting conceptions of interdisciplinarity that we call `early integration' and `late integration', the latter pleading for a strong disciplinary basis of interdisciplinary projects, whereas the former advocates dismissing disciplinary approaches right from the start. As a prominent representative of transdisciplinary science, climate research is considered as a case study. It is at least questionable whether a weakening or erosion of disciplinary approaches can be diagnosed in this field. We argue that the demand for `socially robust knowledge' that makes transdisciplinary science inevitable, as is claimed by Nowotny, does not imply a weakening of the disciplinary structure of science.